We've discovered the entire plot for the single-player campaign

By using information hidden in the Halo 3 Beta code, we've managed to put together a guide to the story, including the locations, battles and a couple of horrifying twists to boot. Can't wait until September to find out how the story ends? Then read on, cautiously (warning: massive spoilers abound!). You've been warned.

Level One

The story: Somewhere in the African jungle you, as the Chief, make a somewhat unexpected landing. The Planet Earth is overrun with the Covenant, and you're ill-equipped - so making your way to a UNSC stronghold to regroup and reload is vital.

The evidence: In one of the first pictures of the level now officially dubbed Sierra117, we saw the Chief's armoured hand rising in front of his face (echoing the CGI trailer released last year) during a rainstorm in the jungle. It would seem his landing was a little rough. The second picture, taken from Bungie's Brute documentary clearly shows an early jungle environment and several Brutes patrolling the area.

The gameplay: Expect this first level to play out in much the same way as Master Chief's crash landing onto the original Halo back in the first game. He must traverse huge organic environments, as he attempts to rendezvous with the human resistance at a nearby UNSC base, locating marines and picking off enemies along the way. This acts as your training mission too - as the Achievements state - so you'll be ushered in fairly gently.